Electrical insulator contamination shield



July 26, 1960 c. M. WAGNER 2,946,841

ELECTRICAL INsuLAToR coN'rAMINATroN SHIELD Filed may 7, 195'/ NVENTOR.hatln M Wa ne D United States Patent G 2,946,841 ELECTRICAL INSULATORCONTAMINATION SHIELD CharlieMifWagne'n-MS 'Hoffman St.,

` Corpus Christi, Tex.

Filed May 7,1957,` "Seri No. 657,654

2 Claims. (Cl. 174-139) This invention relates to improvements inelectrical insulators and more particularly to shields for protectinginsulator surfaces against contamination from dust and sand particles,chemical deposits such as salt, and moisture such as fog.

Considerable damage to electric power transmission lines has been causedby insulator tlashovers and pole lires resulting from contamination ofinsulator surfaces especially in areas along the Gulf Coast where theatmosphere contains salty moisture and some crude petroleum mixed withsand which is blown against and forms deposits on electric poles,insulators and cross-arms.

Attempts have been made to solve the problem of insulator contaminationin some instances by subjecting the insulator surfaces to periodicwashing, abrasive blasting, by replacement of the insulators themselvesor by the use of smooth protective coatings intended to reduce surfacedeposits. In other instances, oversize insulators have been used to theend that their effectiveness on contamination will approximate that ofclean, normal-size insulators. These methods have not been completelysuccessful under adverse conditions and moreover are objectionable froman economic standpoint in that they materially increase the cost oftransmission of electric energy.

The primary object of the present invention is to provide means forprotecting electrical insulators from surface contamination in aneffective and economically feasible manner.

Another important object of the invention is the provision ofcontamination shields that are readily applicable to electric insulatorsalready in use on transmission lines.

Other objects and advantages of the invention will become apparentduring the course of the following detailed description taken inconnection with the accompanying drawing forming a part of thespecification and in which drawing,

Fig. 1 is a view in side elevation of an electric insulator and showingthe application of one segment of a two-segment insulator shieldthereto.

Fig. 2 is a horizontal cross sectional view of the insulator shield ofFig. l, the view being taken substantially on the line 2 2 of Fig. 3.

Fig. 3 is a side elevational view of the insulator shield shown in Figs.1 and 2.

Fig. 4 is a view in side elevational of a two-unit string of suspensioninsulators and showing the application of one segment of a two-segmentinsulator shield thereto.

Fig. 5 is a horizontal cross sectional view of the insulator shieldshown in Fig. 4, taken substantially on the line 5 5 of Fig. 4.

Fig. 6 is a fragmentary view partly in elevation and partly in centralvertical section of a transformer insulator and contamination shieldtherefor.

In the drawing which for the purpose of illustration shows modifiedforms of the invention, and wherein like reference characters denotecorresponding parts throughout the views, the numeral 10 generallydesignates a Patentedduly 26, 1960 ICC contamination shieldr suitablefor application to a flanged .insulator 11 equipped with downwardlyextending supporting lhardware 12 in its base 13 and provided with :anannular groove 14 at its upper end 15.

.inturned annular top ange `portion 21 dimensioned for engagement withthe upper end .portion 15 of the insulator 11 by seating in the annulargroove 14 therein. The skirt or shell 20 also has a generallycylindrical side portion 22 dimensioned to encircle the insulator inspaced relation thereto so as to define an annular gap 23 at the lowerend portion or base 13 of the insulator, and an inturned annular bottomange portion 24 spaced below the insulator 11 and adapted to define agap 25 relative to the bottom end portion of the insulator and a similarlength gap 26 relative to the insulator hardware 12. In

use of the shield, its bottom flange portion 24 serves as a bale whichtends to prevent the ow of contaminative particles and gases toward theinsulator from below.

For the various sizes of insulators these shields will vary in size inaccordance with the physical dimensions of the insulator and thenecessary clearance from conducting or grounded hardware as required bythe National Electrical Manufacturers Association standards forlightning gaps at the applied voltage. For example, at 7.2 kv. the gaps23, 25 and 26 should be s/s.

In Figs. 4 and 5 is shown a contamination shield 10A for a two-unitstring suspension insulator 27 and this shield 10A is like thepreviously described contamination shield 10 of Figs. l-3 in itsconstruction and application except that it has a generally spherical orconvex side portion 28 instead of the generally cylindrical side portion22 of the form shown in Figs. 1-3.

Referring now to Fig. 6 there is shown a transformer bushing 30 whichextends through the transformer cover 31 and is equipped with aninsulator 32 provided at its upper end 33 with an annular groove 34 andthe contamination shield 10B mounted in this groove is the same as thepreviously described shield 10 shown in Figs. 1 3 except for increasedclearance around the insulator 32 and the omission of the inturnedbottom flange portion 24 of Figs. 1-3. Instead of the latter, there ismounted on the transformer cover 3.1 and secured in coaxial alignmentwith the insulator 32 and bushing 30 as by an annular retainer 35, acylindrical sleeve 36 of the same material as the previously describedshield 10 and of a diameter intermediate the diameters of thetransformer insulator 32 and of the transformer shield member 10B,providing suitable gaps between the conducting and grounded parts.

In tests of these contamination shields around insulators in an areawhere extensive damage was being experienced due to pole lires caused byunprotected contaminated insulators, no pole lires or ashovers wereobserved, everrunder the most adverse conditions where these shieldswere in use.

Various changes may be made in the forms of invention herein shown anddescribed without departing from the spirit of the invention or thescope of the following claims.

ments together, said segments being formed of Smooth insulative materialand shaped to jointly provide a skirt having an inturned annular topportion for engagement with the upper end portion of the insulator, -agenerally cylindrical side portion encircling the insulator in spacedrelation and an inturned annular bottom -portion spaced from theinsulator Yand defining a gap relative to the insulator hardware, saidgap having a clearance selected as necessary for lightning gaps at theapplied voltage.

2. A contamination shield for an electrical insulator equipped withnormally downwardly extending supporting hardware in its base comprisingtwo longitudinal half segments equipped with snap means releasablysecuring the half segments together, said segments being formed of thinsmooth insulative weather-resistant plastic and shaped to jointlyprovide a skirt having an inturned annular top portion dimensioned forengagement with the upper end portion of the insulator, a generallyspherical or convex side portion dirnensioned to encircle the insulatorin spaced relation thereto, and an inturned annular bottom portionspaced below the insulator to dene a gap relative to the insulatorhardware and serving to inhibit the ow of dust particles and gasestoward the insulator from below, said gap having a clearance selected asnecessary for lightning gaps at the applied voltage.

References Cited in the le of this patent UNITED STATES PATENTS1,806,854 Hesson May 26, 1931 2,699,960 Callery et al. e Ian. 18, 19552,733,416 Evalt Ian. 31, 1956 FOREIGN PATENTS 385,699 Great Britain Ian.5, 1933

